LIN: Class-A Open Mux Standard Gains Momentum
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THE HANSEN REPORT ON AUTOMOTIVE ELECTRONICS. A Business and Technology Newsletter VOL. 13, NO. 3uu RYE, NH USA APRIL 2000 ACC in Europe, LIN: Class-A Open Mux Japan and Soon Standard Gains Momentum in U.S. After more than a decade of competi- u The consortium that founded LIN is tive wrangling that led to few standards made up of several important industry and a poor climate for technological ad- players: Audi, BMW, DaimlerChrysler, Today’s adaptive cruise control systems vancement, the global auto electronics Motorola, Volcano Communications sense what’s ahead of the vehicle and au- industry is coming together as never be- Technologies (LIN’s developer), Volvo tomatically vary the vehicle’s speed to fore. Witness standards for 42 volts, CAN, and VW. Moreover, the founders designed create a safe following distance. Sophisti- MOST (high-speed fiber-optic communi- LIN as an open protocol, and a complete cated forward-looking detection sensors cations), OSEK (operating systems), and engineering environment that will allow use either infrared laser or millimeter AMIC (Automotive Multimedia Interface others to develop low-cost communica- wave (radar) sensors—and in the not-so- Collaboration for plug-and-play infotain- tion buses. LIN will not require users to distant future, some ACC systems will use ment electronics). All of these, with the pay fees or royalties. Silicon will be avail- both—to detect/sense various target ve- exception of AMIC, came out of Europe, able from Motorola, Microchip Technol- hicles ahead. These smart devices assess/ where another promising standard is now ogy and others. measure the kinematic attributes of each emerging: the LIN protocol specification u LIN is destined for production soon. target, such as distance, relative speed and for realtime communications in embedded DaimlerChrysler will be the first carmaker velocity. ACC systems automatically ad- systems. to install LIN nodes, on a new luxury ve- just vehicle speed by limited applications LIN, which stands for local intercon- hicle that Mercedes will introduce in to the brakes or throttle. Some systems nect network, is an inexpensive, low- 2001. BMW and Audi have said that they allow the driver to specify an adjustable speed (1 to 20 kilobits per second) too are committed to putting LIN into vehicle-headway distance to the vehicle Class-A, serial multiplexing protocol. It production vehicles. Non-consortium car- ahead, for example, three headways. was designed to link switches, actuators maker Fiat has said it will likely use LIN. The driver is still expected to be alert and sensors into a sub-bus that connects In the U.S., DaimlerChrysler-Auburn and responsible to hazards in the path of to the main bus, usually a CAN bus. Ve- Turn to LIN, page 2 the vehicle, particularly because ACC hicle assembly units that could benefit obstacle-detection algorithms currently from a LIN sub-bus are door, roof, steering LIN Protocol Specification disregard nonmoving objects, even if fixed column, seat, climate control, switch in the vehicle’s path. For example, as a panel and intelligent wipers. For example, Definition: An open, Class-A, single-wire, vehicle goes around a curve, the ACC the mounted switches in a steering wheel serial multiplexing bus, based on common system would look straight ahead and assembly—wipers, headlight, turn signal, UART SCI hardware, with speeds from sense many fixed objects, such as trees and horn and cruise-control—could be linked 1 kbps to 20 kbps. LIN (local interconnect buildings that are actually beside the road. digitally on a single wire LIN bus. LIN, network) was designed to link switch Such objects are not, of course, hazards to not designed exclusively for auto applica- changes to actuators such as motors and the driver paying attention. Given the tions, also applies to industrial electronics. lights, events which happen at low speeds, potential threat of liability lawsuits from While SAE has worked unsuccessfully measured in hundreds of milliseconds. inattentive drivers using such systems, in the past to establish a Class-A standard Consortium Founders: Audi, BMW, carmakers around the world are conserva- and while several Class-A multiplexing DaimlerChrysler, Motorola, Volcano tively introducing ACC as a convenience protocols are in use around the world to- Communications Technologies (LIN’s feature. While not called a safety feature, day, none has sufficient prominence to be developer), Volkswagen and Volvo today’s adaptive cruise control systems considered a global standard. The LIN Web Site: www.lin-subbus.org should be safer than conventional cruise protocol could become that standard; it To Discuss the Specification: Please control systems, which do not see objects has a number of things going for it: contact Antal Rajnak (VCT, Gothenburg at all. u LIN will reduce the cost of Class-A Sweden) by phone, 46 31 451 116; email The first ACC systems introduced in multiplexing. By complementing, not [email protected]. Or contact Bernd the West used radar technology—to “see” competing with higher-speed multiplexing Rucha (Motorola GmbH, Munich, Germany) through fog—but now carmakers are will- standards, like CAN and MOST, LIN will by phone, 49 89 92103 395; email ing to introduce laser technology, less facilitate networks that do not need high [email protected]. Turn to ACC, page 2 bandwidth, complexity and performance. ACC... Continued from page 1 expensive than millimeter-wave radar. priced, including VAT, (value-added tax) visibility-limitation feature that advises With laser sensors, carmakers can bring at £1,400 ($2,212). Just this April, BMW drivers not to exceed certain speeds in fog. ACC to a broader range of consumers. introduced on the 7-series a Bosch radar The other key supplier of production Back in August 1997, an infrared laser ACC system for DM 3,800 ($1,862). In ACC systems in the West is Delphi Auto- ACC system was introduced on Toyota the United States in the fall of 2000, motive Systems (Troy, Michigan). Delphi Celsiors in Japan. Toyota has added ACC Mercedes will introduce Distronic on the plans to offer some ACC products with as an option to one model each year, and S- and CL-Classes. Mercedes expects to infrared laser (lidar) sensors and others over that period, about 4,000 ACC- expand availability to other models in the with millimeter-wave sensors. By 2002, equipped vehicles have sold in Japan. On United States. Delphi will supply a laser ACC system for January 1, 2000, the Estima model was ADC (Automotive Distance Con- mid-sized Opel models on the Epsilon offered with ACC as an option for trols) makes Mercedes ACC systems. platform. Omega and Vectra are built on ¥106,000 ($1,005). ADC (Lindau, Germany) is the joint ven- the Epsilon platform. Delphi will make In Europe, Mercedes was the first car- ture of Temic, a DaimlerChrysler division, less-expensive laser sensors so ACC sys- maker to go into production with an ACC with 70% and Leica with 30%. In 2001, tems can reach beyond upscale consumers. system, its radar Distronic system, intro- ADC will supply a low-cost, laser ACC “In general, there are no significant differ- duced in October 1998 on the MY 1999 system, probably to a carmaker in Europe. ences that can be perceived by the driver S-Class, priced at about DM 4,000 According to ADC, infrared sensors are while using an ACC system [that] uses ($1,960). Distronic is now available on nearly half the price of radar, so an IR either object-detection technology,” con- the CL as well. Jaguar, in September ACC system might retail for $800 to cluded Delphi engineers in SAE paper 1999, introduced a Delphi Automotive $1,000. Although IR laser sensors cannot 2000-01-0345, “Comparison of Lidar- Systems radar ACC system in the MY see through dense fog, their sensitivity to Based and Radar-Based Adaptive Cruise 2000 XKR in the UK and Germany, the existence of fog is used by ADC as a Continued on page 8 LIN... Continued from page 1 Hills, Ford and GM are looking seriously the distributed realtime architecture of the API (application program interface) speci- at the LIN specification. There is interest electrical system in the Volvo S80, which fication will be available, as well as a stan- in Japan also: Engineers at Denso, Toyota, entered production in March 1998. Volvo dard development-tool interface. For more Nissan and Honda are among the 150 Bus Corporation will use the technology information or to register for specifica- requesting copies of the specification so in its new generation of city buses and tions, visit www.lin-subbus.org. u far. In the U.S., Yazaki is anticipating that coaches. it will be asked to develop gateways that Located in Gothenburg, Sweden, VCT link LIN to other vehicle buses, CAN for is privately owned, founded in 1998 by THE HANSEN REPORT ON instance. Antal Rajnak and Dr. Ken Tindell, man- AUTOMOTIVE ELECTRONICS DaimlerChrysler expects that the com- aging director of Northern Realtime Ap- munications cost per LIN node will be plications. Because “software complexity is © 2000 Paul Hansen Associates, 11 Went- “two-to-three times lower when compared expected to increase by a factor of over 25 worth Road, Rye, NH 03870, USA; Tele- to CAN.” The carmaker expects to use compared with our most advanced prod- phone: 603-431-5859. Fax: 603-431-5791. between 3 and 10 LIN nodes per vehicle. ucts to date,” and because signaling re- E-mail: [email protected]. All rights If LIN becomes widely used, new mecha- quirements are expected to grow by 7% to reserved. Materials may not be reproduced tronic components like smart sensors, 10% annually, VCT’s founders believed in any form without written permission.